The Shimano SPD SH51 cleats are the most commonly used, almost always found in Shimano clipless pedal packages.
These cleats have a "unidirectional" release, meaning they only release when you rotate your heel outwards.
SPD cleats have been specifically designed to match SHIMANO pedals and avoid damage: this is the great advantage of having components from a single supplier.

• Without specific locking nut
• Cold forged and heat treated to increase durability and rigidity for demanding use even in extreme conditions
• Unidirectional (lateral) release: they only release when you rotate your heel outwards
• Angular freedom: 4°